Three elements are required for a fire to exist and flourish; fuel, heat, and oxygen. Fuel is something that will burn in the presence of heat. When combined with oxygen, the fire thereby releases more heat and, as a result, reduces itself to other chemical compounds. Heat can be considered the catalyst that accelerates the combining of oxygen with fuel, which in turn, releases more heat. The action of oxygen combining chemically with other substances through the process of oxidation accompanied by a noticeable release of heat and light, is called combustion or burning. Remove any one of these necessary elements and the fire goes out.
The National Fire Protection Association has classified fires into three basic types; Class A, Class B, and Class C fires. Class A fires include all ordinary combustible materials such as wood, cloth, paper, upholstery materials, etc. Class B fires include all flammable petroleum products or other flammable or combustible liquids, greases, solvents, paints, etc. Class C fires include energized electrical equipment. There are various forms of extinguishing media suitable for each class of fire. In Class C fires the electrical non conductivity of the extinguishing media is of importance. In most cases, where electrical equipment involved in a Class C fire is de-energized, extinguishers suitable for use on Class A or B fires may be employed effectively.
A fourth class of fire, Class D fire, is defined as fire in flammable metal. Class D fires are not considered a basic type of fire since they are generally caused by a Class A, B or C fire. Usually, Class D fires involve magnesium.
It is known that each combustible material, whether it be a solid, liquid, or gas, has a flame or self-ignition point. When the combustible material is maintained at a temperature below this flame point, it will not burn. Thereby, most prior art methods for extinguishing fires attempt to cool the burning material below the flame point. Class A fires respond best to water or water-type extinguishers that cool the fuel below combustion temperatures. Class B and Class C extinguishers are also effective, but are not equal to the wetting/cooling action of a class A extinguisher.
Class B fires respond to carbon dioxide (CO2), halogenated hydrocarbons (halons) and dry chemicals, all of which displace the oxygen in the air and thereby make combustion impossible. Foam is effective, especially when used in large quantities. Water is ineffective on Class B fires because of the immiscibility of oil and water and may even cause the fire to spread.
Class C fires involving electrical wiring and equipment respond best to CO2, which displaces the oxygen in the atmosphere, making combustion difficult. Dry chemicals are also effective on Class C fires but have the disadvantage of contaminating the local area with powder. Also, if used on wet and energized electrical equipment, dry chemicals may aggravate electrical current leakage. Water or foam are not acceptable agents for use on electrical equipment fires.
Class D fires respond to the application of dry powder, which prevents oxidation and the resulting flame. The application of water on a metal fire is to be avoided because it will cause the fire to burn more violently and can cause explosions.
The most common fire fighting agents are thus water and water-based agents, dry chemicals, and gas. Water and water-based agents are typically used on carbonaceous fires. Water extinguishes a fire by cooling the fuel below the flame point or combustion temperature. The disadvantage of water and water-based agents is that water is not effective on all combustible materials. In addition, large quantities of water are not always available. While dry chemicals offer the advantage of being nonconductors of electricity, they tend to be environmentally unfriendly and hazardous to fire fighters. Gases such as carbon dioxide and halons are toxic and, thus, environmentally unfriendly.
Extinguishing Class B liquid fires presents unique difficulties to fire fighters. With respect to pools of burning liquid, combustion takes place adjacent to the surface of the liquid due to evaporation of the liquid into the air. While foam has been used in the past to smother the flame on liquid fires, it has the disadvantage of requiring substantial amounts of foam material to completely extinguish the fire. Another method gaining rapid commercial acceptance utilizes a chemical that causes a film and foam layer on top of the liquid pool to interrupt evaporation. This chemical is commonly known as aqueous film-forming foam (AFFF). The disadvantages of AFFF are that it requires a special nozzle to apply the agent, the agent takes a substantial amount of time to build a foam layer sufficiently thick to extinguish the flames, and it does not lower the temperature of the liquid pool, presenting the danger of reignition when the liquid fuel is agitated. Self-propelled, three-dimensional liquid fires, such as oil and gas wellhead fires, are not extinguishable using foam because the liquid is expelled into the air at a high rate from the wellhead, with the residue forming burning liquid pools on the ground. This type of fire is extremely hot and requires very large amounts of fire fighting agent to permanently extinguish the fire. One method for extinguishing oil and gas wellhead fires uses an explosive charge that is detonated immediately above the wellhead to force the flame front away from the wellhead area. This temporarily creates a vacuum that deprives the fire of oxygen. If the liquid fuel is not immediately doused and cooled with a fire fighting agent, the returning air rushing in to fill the vacuum can cause the hot liquid fuel to reignite. This particular method is extremely dangerous and also requires substantial amounts of fire fighting agent.
Fighting wildfires also has its difficulties, due to uncontrollable winds which can easily spread a fire and due to the potentially large amount of dry and combustible vegetation. Currently, one of the common fire fighting products used today is Phos-Chek. Phos-Chek fire retardants are manufactured as dry powders or as concentrated liquids and diluted with water prior to use. The retardant is applied directly to or ahead of wildfires and to homes and vegetation by ground crews and aerial firefighting units, using either fixed-wing or rotary-wing aircraft. It is a very common site to watch on the television news reports of the various colored Phos-chek mixtures being selectively dropped upon various fires and other targeted areas.
Phos-chek is currently produced in several colors, including an off-white color, a red iron oxide, and a fugitive mixture that is colored red when dispersed but gradually fades to an earth-tone when exposed to sunlight. The red color aids aircrews in targeting drops of retardant.
Some of the main components of Phos-Chek retardants include ammonium polyphosphate, diammonium phosphate, diammonium sulfate, monoammonium phosphate, attapulgus clay, guar gum (or a derivative of guar gum), and various trade secret performance additives. Fire retardants are manufactured as several different formulations with varying proportions of the above components. The phosphate and sulfate salts act as fire retardants and prevent combustion of cellulosic materials. Guar gum and clay are thickening agents to prevent dispersal of the retardant after it is dropped from the plane. Other ingredients include corrosion inhibitors and flow conditioners such as Silica. Phos-Chek WD-881 is mixture of anionic surfactants, foam stabilizers, and solvents including hexylene glycol. As fire-fighting foam, it is used as a class B short-term fire suppressant.
Unfortunately, Phos-chek has major drawbacks. It is only a short-term fire suppressant and is not applied well before a fire starts. The effectiveness of Phos-chek quickly deteriorates over time and cannot be used in a purely preventative measure before a fire is even anticipated. Phos-chek also stains the ground and surfaces it is placed upon. Phos-chek also when dry becomes the consistency of concrete and is extremely difficult to clean thereafter. Finally, Phos-chek when mixed with water can not be stored for short or prolonged periods and must be used or discarded immediately. Accordingly, it is not used by residents who want to take proactive steps to protect their residences even before a fire has started.
As can be seen, fighting fires correctly is extremely difficult. It is therefore desired that the fire never starts in the first place. Accordingly, there is a need for a fire suppression mixture that can be applied as a preventative measure to prevent a fire from occurring. Furthermore, there is a need for this mixture to be clear and free from color staining the surfaces it is applied to. Additionally, it would be desirous for the mixture to be environmental friendly and simply breakdown chemically and wash away the next time it rains. The present invention fulfills these needs and provides other related advantages.